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UNIVERSAL JOINT. I

No. 381,348. a Patented Apr l'i, 1888.

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UNiTED STATES k PATE T I OFFioE. v f v,

OLIVER N. EATON, on NEW YORK, N. Y.

UNIVERSAL JOINT. F

SPECIFICATION forming part of Letters Patent No. 381,318, dated'Aprill7, 1888. I 1

Application tiled July 11, 1887. Serial iNofQ-hLQBfi. (No model.)

adapted to Folding Chairs, Desks, 8nd, of

which the following is a description in such full, clear, and exact terms as to enable any one skilled in the art to make and .use' the same, referencebeing had to the accompanying two sheets of drawings, wherein like letters indicate corresponding partsthroughout the several views. 7

:Sheet 1 of the drawings illustrates my improved ball-"and-socket joint; and Sheet2 shows its adaptation to a chair with a folding seat,

and analogous adaptations to similar uses in.

folding s'ettees, desks, carriage-tops, and elsewhere are easily within ordinary mechanical skill.

Considering Sheet 1, Figure 1 shows a central vertical section of a universal joint con- 'der to facilitate insertion and removal.

sisting-of ball A and socket B, of my improved coustructiomand-Fig. 2 shows a horizontal section of the ball A atits greatest diameter, as indicated by dotted lines in Fig. 1.. The

two chief peculiarities of construction are the substitution of a substantially double-convex ball or button moving in a double concave socket of corresponding shape, instead of the ordinary corresponding spherical shapes, and the removal of a suitable section, a, from one side of such double-convex ball A,to allow introduction tothe socket B and removal therefrom at will. The socket B has the shape shown in section, depending, of course, uponthe convexities of the ball desirable or neces sary for the particular use; but generally the bottom of the socket should be more concave than the bottom of the ball is convex, in or- The ball A is shaped substantially like a doubleconvex lens,with a portion of one edge, a, cut

. off straight or with a little inward curve, as

shown by the horizontal section in Fig. 2. The same purpose will be served and object accomplished by a suitable notch, b, in the rim of the socket B, as shown in plan by Fig. 3.

Between the ball and socket is an elasticplate,

or disk, 0, which fits across the greatest diameter of the socket, and has such relation to the ball when seated in the socket "that con-1 A stant pressure results to keep the ball against the edges of the socket. 1 This plateT-orldisk may be omitted where weight may beused instead, as when something is suspended by the joint, or in equivalent instances. Themethod of inserting theball intothe socket'is to in.- troduceone of the corners formed by the out on the edge of the ball-for. example, the up:- per corner into the socket- -pushingfbackt. the spring-disk, then turn or twist the ball, as indicated by the arrow in Fig.2, around into the socket, the remainder being easily pushed into proper place, whereupon the elastic disk springs back, forcing the ball "and socket into juxtaposition and firmly'keeping it, while allowing freedom of movement within the limits of each particular construction. The motion is reversed in removal. It is obvious that the shapeof such a ball or button may vary fromn'early flat to nearly spherical and the shape of the socket be modifiedcorrespondingl y, accordingto the range of movement desired in a particular location. For instance,the upper sides of the socket may be straight,converging from the middle to the top at the-edges or'me socket, as shown, or, suitably curved, and the ball may 'b emadc quite flat where the movement is in parallel planes and wear is considerable. 'Suchmodifications are contemplated in my invention and included in the terms used in the claims. The size and shape of the section to becut from the side or edge of the ball or button also depend upon the size and shape of the balla'nd the socket, or the section may be taken from the rimof the socket,as suggested. These details, however, are only in special constructions and arealready sufficiently pointed'out;

showsmetallic covering forexposed. nuts. I The frame F is provided on each side with socket'B to hold ball A attached to seat-sup- 9 Sheet 2-of the drawings shows thejoi'nt port D, and with a flange or stop, E, to limit the folding of the seat and hold it horizontal. The seat-support D has a flange with slots d d d for aflixing the seat with bolts and allowing for variations in alignment,and any necessary stren gthenin grib m ay take the courseindicated by the dotted lines in Fig. 6. The ball-andsocket joint is constructed and operated as before described. Each frame F is also provided oneach side with three flanges, the central one, e, bored, and the outside ones, ff,

slotted, as shown distinctly in Fig. 5, whereby the chair-back may be hung between the frames by bolts through the holes in the central flanges, e e, and adjusted in any position by bolts in the slotted fiangesff.

The chair-back I is of the shape outlined in Fig. 7, with straight parallel sides above the middle and converging below suflicient to allow for variations necessary when chairs are arranged in circular rows. It is obvious that chairs of such patterns may be set in either straight or curved rows and accommodate themselves to varying lines necessary in each case. p r

The floor itself upon which circular rows of chairs are placed is often raised rearward,and sometimes in the center also, causing additional variations of the juncture of the backs and frames. Straight square backs cannot then be used without more or less manual modifications or shaping to each-situation, involving additional labor and consequent cost. \Vhere the floor is raised centrally and there are straight rows of chairs across, the frames are necessarily farther apart at the top than at the bottom proportionately to the rise, and where the floor slopes downward toward the front and the chairs are in circular rows across there is the same re-, sult and remedy required. These remarks apply also to the juncture of the seat-supports with the chair-frames with reference to the various planes of movement in turning the seat up and down required in the varying situations. A joint or hinge admitting only of action or movements in parallel planes and It isfied, allparts mutually and reciprocally adjust themselves to the different angles and conditions required by situations varying from straight lines to circles, which is an impossithan bottom, to receive a board, H,an d retain it when raised up and thereby wedged into position. The ends of such boards or so-called hat-protectors would be adjacent in a row of chairs, as indicated by the dotted lines in Fig. 5. The top of the arm J has slotted pins or studs on each side, as shown plainly in Fig. 8, which fit into corresponding holes in the bottom of the wooden cushion commonly attached, so that. it may be easily afiixed by screws.

As shown in Fig. 9, the nuts L of the bolts M, holding the chair-back in place or elsewhere exposed, are covered with a metal cap, .N, which may be made ornamental. I What I claim as novel, useful, and my invention is- 1. A universal joint consisting of a doubleconvex ball or button with a suitable segment removed from its side, in combination with a corresponding double-concave socket-,substantially'as specified.

2. A universal joint consisting of adouble-.

convex ball or button with a suitable section removed from its side, in combination with a ICC manner and for the purpose substantially as specified.

4. As combined by universal joints, a'chair frame and folding seat, saidframe provided on each side with a perforated flange in the .mid-

die and slotted flange above and below, in combination with a chair-back having sides converging below the middle, in the manner and for the purpose substantially as specified.

OLIVER N. EATON.

\Vitnesses:

WM.:F. PYNE, GEO. WHITFIELD BROW'N, J r. 

